Cite as:
Festman Y, Ahissar M, 2003, "Attentional effects on adaptation to gratings" Perception 32 ECVP Abstract Supplement

Attentional effects on adaptation to gratings

Y Festman, M Ahissar

We studied attentional effects on the adaptation of gratings. Contrast threshold and perceived vertical orientation were assessed before and after exposure to a sequence of adapting gratings (two sinusoidal gratings of 5 cycles deg^-1, subtending 4.5 deg, duration 500 ms, ISI 500 ms, centred on a small fixation circle). The subsequent test grating varied either in contrast (contrast threshold) or in orientation (perceived vertical). Attention to adapting gratings was manipulated in five conditions: no task during adapting period (1), same/different discrimination with respect to contrast or orientation of adapting gratings (2 - 3), ditto with respect to orientation or luminance of fixation circle (4 - 5). The results show the expected contrast threshold elevation (CTE) and tilt aftereffect (TAE) due to adaptation. With any task during the adapting period (conditions 2 - 5), CTE but not TAE was significantly larger than with passive viewing (condition 1). We attribute this to the alertness component of attention, which increases activity and consequently enhances adaptation. The differential effect on CTE and TAE is expected because the former reflects absolute and the latter relative sensitivity of orientation-tuned channels (Coltheart, 1971 Psychological Review 78 114 - 121). Interestingly, attending the fixation circle (conditions 4 - 5) rather than the adapting gratings (conditions 2 - 3) decreases TAE significantly, while leaving CTE unchanged, suggesting that selective attention modulates only the former. Our results imply a hierarchy of adaptation mechanisms, with contrast adaptation at a lower (preattentive) level and orientation adaptation at a higher (attentive) level of visual processing.

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